1. Field of the Invention
The present invention relates to an optical image stabilizer for an optical instrument and a method of controlling an optical image stabilizer incorporated in an optical instrument.
2. Description of the Related Art
This type of optical image stabilizer for an optical instrument typically operates to stabilize an object image on an imaging surface (imaging plane) by moving a part of an optical system of the optical instrument relative to the optical axis of the optical system in accordance with vibrations applied to the body of the optical instrument, and has often been incorporated especially in a digital camera or a pair of binoculars in recent years.
In a mobile optical instrument such as digital camera and binoculars, there has been a strong demand for an extension of a battery lifetime. Accordingly, there has been a demand for a reduction of power consumption of even the optical image stabilizer. Different types of drive sources such as a drive coil and a stepping motor (pulse motor) have been proposed as a drive source for moving an image-stabilizing optical element in the optical image stabilizer. In the case of a drive coil, the drive coil needs to be energized even when the image-stabilizing optical element is in a halted state in the drive-coil-using optical image stabilizer, whereas a stepping-motor-using optical image stabilizer has an advantage in that the image-stabilizing optical element can be halted without supplying power to the stepping motor when no image stabilizing operation is performed. Nevertheless, the power consumption of the stepping motor tends to be greater than that of the drive coil during an image-stabilizing operation.